Do I need to consider integrating multi-touch into the next generation of my touch products? – Joe Kennedy, New Mexico

Dear Joe:

Touch guy recalls, as a young lad, seeing the brand new and largely passenger free 747’s landing at LAX – this was called the Judas Goat phenomena because no self-respecting airline would be without the behemoth, even though they hardly had enough money to buy one and there was not enough passengers to fill one.

The same concept applies to touch screens. Multi-touch projected capacitive has rapidly grown to be the second largest selling touch-technology (behind analog resistive), even though, other than pinch and expand, there are hardly any software programs that make use of all those fingers. Microsoft has demanded 10-finger touch with lightening quick response to even be considered worthy of being certified.

So, yes, Joe, I do not even have to ask what your product is, you have to do it, and hope that the need comes – just like the passengers that eventually filled the 747’s… There are two real and important reasons why you need to do it, the most important is that projected capacitive will not wear out and the second is that the image quality is really excellent. Add to that, the prices are expected to fall by 50% sometime this year and you have everything you need to make the plunge. And if your application requires pressure sensing (screwdrivers, long fingernails and scalpels), you can now pick the MARS multi-touch product.

Until next time,
Touch Guy

How should I pick a touch screen company? – Confused in Schenectady

Dear Confused:

Touch Guy is honored that you would pick him to say anything other than, “the only name you need to know is Touch International!” And Touch Guy will admit, after reflecting upon your question, coming up with an answer was daunting. There are more than 100, possibly as many as 200 touch screen companies around the world. They range from companies that focus on selling fully integrated systems all the way to “village” companies that somehow sell 4-wire touch panels at prices below the material cost.

First, because you are asking the question, Touch Guy will assume you are probably working on your first touch project and have not yet been swayed toward or against a specific touch solution (this is good because that means you have an open mind). To start, narrow down the types of touch technology that seem best for you. Read my white paper, “Choosing the Right Touch Technology,” check out products similar to yours to see what they use and then it is off to the web to search for suppliers. While there are several of types of touch, resistive, capacitive and IR have long been the top solutions. Less used but still common are acoustic and optical (camera). Resistive still rules but most new projects use the iphone-type technology called projected capacitive.

The touch screen business is very competitive so apples-to-apples pricing will not vary much. For complicated designs and touch-neophytes, the US suppliers are probably best and for routine, higher volume products, the Taiwanese are going to come through for you. For price, the Chinese suppliers will be your best choice but I suggest waiting until your second project to go that route.

In shorter words, see what your competitors are using, read about touch, call a supplier in your region, and find someone who sounds like they want to help!

Wow, that was a hard question.

Until next time,
Touch Guy

Can I hurt a touch screen by touching it? – Ben Harris, Cucamonga, CA

Ah Ben, the question we Touch guys have always feared. I assume your question is akin to asking, “Does it hurt a tire if you use it on the road?” However, I think what you really mean is, “Does touching the screen wear it out”?

Well in the early days of touch (1970’s), some touch sensors did wear out when finger oils, ladies’ hand creams and Hawaiian-breezes corroded the thin films. (Hmm, wonder what those creams did to their hands?)

Today, all sensors are advertised to withstand a minimum of 5 million touches. It is even rumored that the president of one unnamed touch company (Microtouch) hired a homeless guy to actually touch the screen that many times. Each of the technologies wear out differently and there is a difference between electrical wear (it does not work anymore) and cosmetic wear (the display is hard to read).

The newest entry into the touch arena is also the most vulnerable to electrical failure. When the in-cell technology fails, it is going to take your display with it, so it’s a double whammy on the checkbook. This happens because you must actually touch and depress the LCD surface itself, which puddles the liquid crystal and scratches the first surface. (Remember your mother telling you to keep your hands off the TV?)

Surface capacitive is the most vulnerable to electrical wear. Touching the same spot multiple times will actually wear through the thin film, down to the glass substrate, rendering it non-linear. Of course, a big scratch from a diamond ring will do-it-in quickly. And bye-bye to SAW technology when that same guy puts a big ‘ol scratch in it too.

In terms of electrical and cosmetic failures, resistive 4-wire touch screens are the most vulnerable. Touching in one place will rub a shiny spot in the hard coat of the top polyester (PET) layer. Touching in this same spot will also wear and crack the top conductive layer and leave it an electrical basket-case. The same number of touches on a 5-wire resistive will not damage it electrically; however the same glossy spot will appear.

In the end, the winners in the wear-me-out contest are projected capacitive (p-cap) and Infra-Red which work without needing to touch anything. Nothing to wear, no electrical surface to scratch and thus these two touch technologies can advertise infinite electrical life.

So Benny, as is the case with that tire, there are 10,000 mile touch screens and 1,000,000 mile touch screens, it just depends.

Until next time,
Touch Guy